This section provides background information related to the present disclosure which is not necessarily prior art.
One type of grain level switch involves the use of a mercury electrical contact switch. Such a switch is typically coupled at one end of a horizontally extending rotatable or pivotable rod. A paddle extends from the horizontal rod to rotate or pivot the rod when it is contacted by grain. There are environmental problems associated with the use and disposal of mercury electrical contact switches. Another disadvantage with such arrangements is that the switch is only responsive to a component of grain flow that is moving perpendicular to the paddle.
Another type of grain level switch uses a rotating paddle coupled to a motor via a slip clutch. When grain surrounds the rotating paddle causing the clutch to begin to slip, a corresponding grain level is sensed. Turning the motor in order to detect whether grain is present, however, uses electricity unnecessarily, creating a different set of environmental issues. Other disadvantages include high component and maintenance costs, and an undesirable time lag between grain reaching the level of the rotating paddle and the clutch beginning to slip.
Yet another type of grain level switch uses a capacitive sensor. When grain is present adjacent the capacitor, the capacitance reading changes (as compared with air being adjacent the capacitive sensor) resulting in a corresponding signal. Such capacitive sensors can give false readings when the temperature is low or condensation occurs on the sensor.
Thus, it is desirable to provide an improved grain level switch.